Heat generating devices, such as power semiconductor devices, may be coupled to a heat spreader to remove heat and lower the maximum operating temperature of the heat generating device. In some applications, cooling fluid may be used to receive heat generated by the heat generating device by convective thermal transfer, and remove such heat from the heat generating device. In two-phase heat cooling devices, heat transfer is provided by the phase-change of the cooling fluid from a liquid to a vapor by nucleation. Rough or porous surfaces provide additional nucleation sites to encourage boiling. In addition to two-phase heat transfer, jet impingement may also be used to cool a heat generating device by directing impingement jets of cooling fluid onto the heat generating device or a target surface that is thermally coupled to the heat generating device.
Accordingly, a need exists for structures that provide for increased nucleation site density for enhanced thermal performance in two-phase cooling assemblies.